This invention generally relates to a seal between a fixed member and a movable member. More particularly, this invention relates to a finger seal between relatively moveable ducts.
A gas turbine engine typically includes an exhaust duct for directing exhaust gases. Many exhaust duct assemblies include a movable portion for selectively directing the exhaust gases. Such exhaust duct assemblies includes a fixed portion and a movable portion. A seal is required between the fixed and movable portions to prevent intrusion of exhaust gases through the exhaust nozzle assembly at the interface between the fixed and movable portions.
A seal may be provided by a plurality of fingers that are defined by a corresponding plurality of slots. The slots and finger configuration provide for flexing and expansion of the movable member relative to the fixed portion. Known seals utilize staggered overlapping configurations to prevent leakage.
Finger seals are often fabricated in sheet metal and are comprised of machined or photo-etched finger shapes attached to or integral to thin metal laminate rings, stacking the laminates so that the fingers of one laminate overlap the fingers of the adjacent laminates. The stack is held together with mechanical or bonding means including rivets and fasteners.
A finger seal consists of long, pointed “fingers” angled in the direction of the sealing surface or the rotation in applications involving enclosed shafts. Gaps between the fingers allow each finger to flex in response to thermal, dynamic and/or vibratory loads between the two components.
Wear can occur between the fingers and lands that interact with the fingers.